A load of coprolites

The Moa disappeared 600 years ago, but at least one of our native buttercups—the tiny Ceratocephala pungens, found only in the Mackenzie Basin and Central Otago—continues to suffer the consequences.

This is one of the discoveries Jamie Wood has made from his research into coprolites, or fossilised moa droppings, which he conducted for his PhD with the University of Otago. Wood went looking for them in Central Otago, along gorges and under ledges, places where sheep often shelter. “If it’s dry enough for sheep, its probable that birds and moa sheltered there in the past.”

Wood’s digs have yielded around 1500–1800 coprolites, left behind by moa and other extinct birds, ranging from 5 mm sized lumps likely to have been left behind by parakeets, to 10 cm moa droppings. While the coprolites are rock-hard when found, they come up as good as new after being soaked in liquid for a few weeks. Close examina­tion yields all sorts of insights, not only on the habits and habitats of different moa species, but also the impact of their extinction on surviving species.

Such as the aforementioned but­tercup, one of New Zealand’s rarest plants. Unexpectedly high levels of its seeds were found in the moa coprolites. “We were really blown away that these birds would eat such tiny plants,” says Wood. Analysis revealed that the plants contain high levels of calcium. As the coprolites were usually found in nesting areas, it makes sense that moa, when they were about to lay eggs, would boost their calcium levels.

One of the reasons the buttercup is so vulnerable these days is that it doesn’t stand a chance against more invasive plants. (Which explains why the only places it still survives— Cen­tral Otago and the Mackenzie Basin—is where rabbits have decimated much of the competing flora.)

But now scientists know that another key reason is that it is toxic to mammals, and without the moa, there are few ani­mals left to spread its seeds. “It shows how important it is, in the conserva­tion of plants, to understand how they evolved alongside birds,” says Wood.

More revelations about the relation­ship between our extinct fauna and ex­isting flora are to come: Wood and col­leagues at Landcare Research and at the University of Adelaide’s Australian Cen­tre for Ancient DNA (the only custom-built built lab designed to specifically to examine ancient DNA in the southern Hemisphere) received $768,000 in last year’s Marsden funding round.